New Exhaust = Idle Change? - Help

[BAMO]

Pretty much what the title says. I swapped out my old rusted out 1.75" frankenstined exhaust yesterday for a 2" dual exhaust. After about 10 minutes of driving, I noticed the engine start to sputter at idle. (started to notice something amiss about 3 blocks after I started driving).

Once I got home, I adjusted the idle screw on the Rochester GV and issue is resolved (for now anyway). So the question is, would the new exhaust effect the fuel mixture in this way? I've read that it could, since the engine is now breathing better potentially the mixture could/would be too lean as a result.

Thoughts or other likely culprits? Since it is the only thing that changed from day to day figured there had to be a correlation, but figured I'd throw it out there to make sure (not that I don't have other carb tinkering to do, but just want to narrow down the gremlins, or at least their causes.